BELVIDERE — The 2009 fatal explosion at a synthetic quartz manufacturing plant in Belvidere was caused by corrosion in the walls of a pressure vessel that went uninspected for years, officials announced Thursday.

The U.S. Chemical Safety Board determined that staff at NDK Crystal, 701 Crystal Parkway, ignored safety recommendations to inspect the interior walls of the vessels, even after a consultant warned the company about the dangers of the operation.

If someone would have inspected the interior walls of the vessels, he would have learned that the material coating the steel vessel walls was not protecting them from corrosion.

Superheated liquid escaped from inside the vessel Dec. 7, 2009, causing an explosion so powerful that the vessel’s base broke away from its foundation, according to the final report. A seven-foot, 100-pound steel beam was sent flying 650 feet away to the oasis off Interstate 90 where it fatally struck 63-year-old truck driver Ronald Greenfield of Chesterton, Ind.

The thrust also caused an eight-foot tall by four-foot wide, 8,600-pound vessel fragment to break through two concrete walls and land 435 feet from the building. The debris slammed into a nearby business office wall, injuring an employee.

“Who decided to ignore this warning and gamble with people’s lives? What incentives or pressures was he under or she under to choose to ignore this warning? And further, should you be allowed to operate a facility that an insurance company has deemed too unsafe to cover?” board member Beth Rosenberg said.

Gary Vist, attorney representing NDK, said he could not respond to specific concerns raised in the final report because it could influence NDK’s ongoing insurance coverage litigation. However, he said “for anybody to come out and suggest that safety was overlooked or ignored is really preposterous.”

The U.S. Chemical Safety Board approved the following recommendations: prohibit NDK from using existing pressure vessels at the facility for crystal manufacturing, require staff at a new NDK facility to demonstrate that its operations are safer than existing processes and mandate that NDK hire an expert to design a program that oversees any coating used on the new process vessels.

NDK will study the U.S. Chemical Safety Board’s recommendations and determine if it wants to restart its crystal manufacturing operations, Vist said. If the company did, it would likely not operate in Belvidere.

Page 2 of 2 - NDK was warned that its operations weren’t safe for the public.

In January 2007, one of the vessels had an uncontrollable leak, causing hot, caustic material to spray onto the ceiling, according to the final report. No one was injured in the incident.

A consultant hired by NDK determined that stress corrosion cracking caused the incident. The consultant told the company it had “serious reservations” about any of the vessels operating again and that doing so would be a “serious flawed decision and not based on sound engineering analyses.”

“From what we learned, NDK did not feel that the failure scenario listed in the consultant’s letter was privy to the same outcome as stated in the warning,” investigator Lucy Tyler said.

“It was noted by the insurance company that their safety program was somewhat informal, lacking formalized job training, standard operating procedures … this is kind of part of a consistent trend in their performance with their approach to internal safety.”